Artificial limb



April 6, 1943.

ARTIFICIAL LIMB Filed June 17, 1940 Conrad B Johnson and Rg'mord B. Tr aubmam c. B. JOHNSON ETAL Patented Apr. 6, 1943 UNITED ARTIFICIAL LIMB Conrad B. Johnson, Eau Claire, Wis., and Raymond B. Trautman, Minneapolis, Minn.

Application June 17, 1940, Serial No. 340,976

8 Claims.

Our invention relates to improvements in artificial limbs and particularly to the construction of the ankle joint between the foot and shank of an artificial leg.

An object of the invention is to provide an improved artificial leg of light weight and of simple, durable and inexpensive construction having an ankle joint adapted, in life-like manner, .to simulate the action of the human ankle joint, and adapted to render the artificial leg comfortable in wear and of high utility to the user.

A further object of the invention is to provide an artificial leg, as above, in which the ankle joint functions noiselessly, without lubrication or wear, and in a manner in which the foot readily adjusts itself universally to bear flatly on the floor and steadily support the wearer without undue strain on the wearers stump.

Another object of the invention is to provide an artificial leg wherein the ankle joint comprises an elastic medium which universally connects the foot to the shank and which fiexes hingedly in a plane longitudinally of the foot more readily and to a greater extent than otherwise.

A further object of the invention is to provide an artificial leg of the instant nature, wherein stop means are provided to limit, at opposite extremes, said hingedly flexing action of the joint.

An additional object of the invention is to provide such stop means, whereby the hinging of the foot to raise the toe and lower the heel relative to the shank is adjustably arrested, without shock, to meet the particular requirements of the user.

Other objects of the invention reside in the novel combination and arrangements of parts and in the details of construction hereinafter illustrated and/ or described.

In the drawing, Fig. l is a central sectionalview of an artificial leg embodying our invention, the same being taken in a plane longitudinally of the foot; Fi 2 is a sectional View taken as on the line 22 of Fig. 1, and Fig. 3 is a perspective view in detail illustrating the block of elastic material comprising the ankle joint and illustrating, further, the anchoring bolts for securing said block to the shank and foot of said leg.

Referring to the drawing, it will be observed that the illustrated form of our invention includes a shank A, foot B and ankle joint C.

The shank A is a shell-like structure formed from sheet fiber lapped at the back and, as will be readily understood, may be otherwise suitably constructed of any suitable material. Said shank;-

A is hollow at its upper portion to provide a socket ID to receive the stump of the wearer. At the lower portion of the shank A is a plug l I, suitably of wood, which is relatively tough and light in weight, said plug being securely fastened to the shell of the shank in any convenient manner. This plug II is notched transversely thereof at its lower forward portion to provide a downwardly opening recess I2 in the shank A. Said plug II forms the upper wall and rear wall of the recess I2, while the side and forward walls of said recess comprise the lower marginal portion of the shell of the shank A at the sides and front thereof.

The foot B is constructed of any suitable material, preferably wood, which is relativelytough and light in weight. In the top of the foot B is a cavity I 3 having a reduced deepened portion between the toe and heel providing an upwardly opening recess I4, which is similar to and registers with the downwardly opening recess H2 in the plug I l of the shank A. Attached to the bottom of the foot B is a resilient sole-piece I5 of rubber, and sheathing the sides and top of said foot B is a covering I5 of leather which, at its lower marginal portion, is turned in beneath said solepiece l5. A facing ll of leather underlies the resilient sole-piece I5 and the in-turned portion of the foot covering I6.

The ankle joint C is essentially a block of elastic material, such as rubber, and comprises an elongated base section l8, an elongated head section l9, and an elongated web 20 joining said sections from side to side thereof between their ends. In longitudinal cross-section, the elastic block 0 comprising the ankle joint, is I-shaped. Said block C is interposed between the shank A and foot B with the base and head sections I8,

I9 extending longitudinally of the latter and the web 20 extending transversely thereof. Said base section I8 is socketed in the upwardly opening recess 14 in the foot 13 and said head section I9 is socketed in the downwardly opening recess I2 in the shank A. This socketing of the block C of said block C, forwardly of the web 20, and downwardly through the foot 13. The upper end of said bolt 2! has a large, thin head 22 bearing upon said base section [8, the lower end of said bolt 2| being threaded and fitted with a nut 23 which is received in an opening 24 in the resilient sole-piece l and turned up against the bottom of the foot proper. To secure the head section IQ of the block C firmly socketed in the recess I2 in the shank A, a second anchoring bolt 25 is provided. This second bolt 25 extends upwardly through the head section 19 of the block C, for wardly of the web 23 and upwardly through the plug H. The lower end of said bolt 25 has a large, thin head 26 which bears against the lower side of the head section 19 and is threaded at its upper end. This threaded end of the .bolt 25 is fitted with a nut 2'! which is turned down against said plug II, a washer 28 being interposed between said nut 21 and plug I I.

From the foregoing, it will be readily comprehended that the elastic block or joint C, attached to the shank A and foot B, flexibly joins the two for relative universal movement without the one contacting the other. Thus, the elastic block C not only serves to reestablish normal relationship between shank and foot when they are relieved of the weight of the wearer, but also serves as a cushion when subjected to such weight and, further, serves to admit of the flat-footed dispositioning of the foot B under all usual circumstances. With the foot B automatically reestablished in its normal relationship relative to the shank B, the stride of the wearer is readily performed and, to the observer, appears to be entirely natural. With the block C cushioning the wearers weight and flexing to allow the foot to .stay fiat on the ground under such weight, the

wearer is relieved of shocks and jolts in walking and is saved from painful chafing, bruising and jarring on the stump of his leg.

Due to the I-shaped cross-sectional construction of the block 0 and the lengthwise dis-positioning of its web 23 transversely of the foot, said [block flexes more readily fore and aft of the foot than transversely thereof, wherefore the toeing up and down .is attended with less resistance than the sidewise turning of the foot, such action conforming with the action of the human ankle.

During the hinging action between shank A and foot B, longitudinally of the latter, the front portion of the web 20 is compressed and the back .portion thereof stretched or vice versa. Owing to the form of. the block C which, in effect, is

notched as at 28 in the front-thereof and as at 29 in the back, the compressed portion of said web 20 bulges into its respective notch, thereby avoiding any undue impedance to the flexing of said block.

Separate stop means are provided for oppositely limiting the hinging action between the shank A and foot B, both of such means being disposed at the rear of the block C. The stop means for arresting the hinging action in the structure which attends the lowering of the toe and the raising of the heel of the foot B, relative to the shank A, comprises the lower rear or heel portion 30 of the shank A and the heel portion 3| of the foot at the bottom of the cavity l3 therein, said heel portions of said shank and foot being adapted to abut one against the other. The stop means for arresting the hinging action which attends the raising of the toe and the lowering of the heel of the foot B, relative to the shank A, includes a heel cord D simulating the Achilles tendon of the human leg. This heel cord D is contained within upright bores 32, 33, respectively formed in the heel of the foot B and the plug H in the shank A. The body of said cord D is preferably made up of a number of strands 34 of slightly stretchable material such as cotton with the strands looped at the lower end of the cord to provide an eye :1. The upper ends of the strands 34 are set in a threaded ferrule 35. Threaded on said ferrule 35 is a nut 36 having an annular flange 31 supplied with an underfacing 38 of felt or other suitable silencing material, said flange 31 having a seat 38 on the plug II at the bottom of an enlargement 39 to the upper portion of the bore 33 in said plug ll. Sheathing the heel cord D at'the eye d and upwardly therefrom to the ferrule 35 is a covering 40 of leather which binds the strands 34 of said cord together. An anchoring pin 4| extends through the heel of the foot B from side to side thereof spanning the bore 32 in said heel and being threaded through the eye d in the heel cord D. In the normal relationship between the shank A and foot 13 and with the elastic ankle joint C unflexed, the nut 36 is unseated from the seat 33 in the plug II. Changing the hinged relationship, as by lowering the toe of the foot and raising the heel relative to the shank, the heel cord D slides upwardly within the bore 33 of said lplug further unseating said nut 35, the cord, of course, in the unseated position of the nut being ineffective as a stop. However, when the hinged relationship between the shank A and foot B is changed, as by raising the toe of the foot and lowering the heel, relative to the shank, the cord D slides downwardly within said bore 33 bringing the nut 36 against its seat 38*, such seating of the nut causing the cord D to act as a snubber and to arrest further hinging movement between foot and shank. In arresting such movement, the stoppage is yieldingly effected without shock by reason of the stretchable character of the cord D and the compressible character of the joint C. By adjusting the nut 36 on the ferrule 35, any user wearing any shoe of any heel-lift height, may provide for an earlier or later snublbing action by the heel cord D that is best suited to his comfort.

It is to be observed that our improved artificial leg com-prises but a minimum number of parts; that said parts are easily assembled and easily taken apart for replacement or repair, and that the parts work quietly without lubrication. Further, it will be readily comprehended that the action of our improved structure closely simulates that of the human leg, the wearer being free from shocks in walking and free from chafing, binding and bruising of his stump against the socketforming shank A.

Changes in the specific form. of our invention, as herein disclosed, may be made within the-scope of what is claimed without departing from'the spirit of our invention.

Having described our invention, what we claim as new and desire to protect by Letters Patent is:

1. In an artificial leg having a foot and a shank as members thereof, an ankle joint structure hingedly tying said foot to said shankand consisting of a block of elastic material formed with a base flange and a head fiange means for rigidly anchoring saidbase fiange to saidfoot, and means for rigidly anchoring said head flange to said shank, said block rendering the connection between shank and foot elastic, whereby theone leg member may be moved by force hingedly relative to the other, but upon cessation of such force will resume its initial relationship with respect to such other member.

2. In an artificial leg having a foot and a shank as elements thereof, an ankle joint structure connecting said foot and shank together and yieldingly maintaining the same in a predetermined life-like relationship, said structure including a block of elastic material formed with a base flange and a head flange, said joint structure further including two bolts for independently bolting said base flange and head flange to said foot and shank, respectively, said joint structure admitting of the enforced hinging of one leg element relative to the other.

3. In an artificial leg having a foot and a shank as elements thereof, an ankle joint member hingedly tying said foot and shank together and yieldingly maintaining the same in a predetermined life-like relationship, said member consisting of a block of elastic material which will be compressed at one side thereof and stretched at the opposite side upon the enforced hinging of the one leg element relative to the other.

4. In an artificial leg having a foot and a shank as elements thereof, an ankle joint member of elastic material hingedly tying said foot and shank together, said member yieldingly maintaining said foot and shank in a predetermined life-like relationship and admitting of the enforced hinging of the one leg element relative to the other.

5. An artificial leg having a foot and a shank, an ankle joint member interposed therebetween and tying the same together, said member consisting of a block of elastic material anchored at its lower portion to the foot and at its upper portion to the shank universally to hinge said foot resiliently to said shank, said member hingedly maintaining the foot and shank relative to each other in one relationship and yielding in accommodation of the enforced disturbance of such relationship under the shifting movements of the wearer, such yielding of said member being attended with the stretching of the same at one side and the compression thereof at its opposite side, said member being so proportioned and so arranged relative to said foot and shank that the yielding thereof is more readily effected longitudinally of said foot than transversely thereof.

6. An artificial leg having a foot and a shank,

an ankle joint member interposed therebetween and tying the same together, said member consisting of a block of elastic material anchored at its lower portion to the foot and at its upper portion to the shank universally to hinge said foot resiliently to said shank, said member hingedly maintaining the foot and shank relative to each other in one relationship and yielding in accommodation of the enforced disturbance of such relationship under the shifting movements of the wearer, such yielding of said member being attended with the stretching of the same at one side and the compression thereof at its opposite side.

7. In an artificial leg having a foot and a shank, an ankle joint member of elastic material consisting of elongated base and head sections and a web intermediately thereof joining the same together, said base and head sections being socketed in and anchored to said foot and shank, respectively. in lengthwise disposition longitudinally of the foot with said web disposed in the direction of its length transversely of said foot, said member elastically tying said foot and shank together for relative universal movement and more readily admitting of relative movement therebetween lengthwise of the foot than transversely thereof.

8. In an artificial leg having a foot and a shank, an ankle joint member of resilient material seated on said foot and supporting said shank, said member consisting of elongated base and head sections and a web intermediately thereof joining the same together, said base and head sections being socketed in said foot and shank, respectively, in lengthwise disposition longitudinally of the foot with said web disposed in the direction of its length transversely of said foot, said member admitting of relative universal movement between said foot and shank and more readily admitting of relative movement therebetween lengthwise of the foot than transversely thereof.

CONRAD B. JOHNSON. RAYMOND B. 'IRAUTMAN. 

